Custom SQL cannot be used when connecting to Salesforce. All objects will be downloaded in their entirety. They can be incrementally updated however, and a calculated field to get this data to appear can be created after the data has been imported into Tableau.
Hope this helps!
Thank you very much for your answer.
What I am trying to accomplish is described in a previous topic: http://community.tableau.com/thread/124437, The solution suggested works perfectly with a SQL server connection using a custom SQL.
I want to do the same using a Salesforce connection instead, however in the Salesforce connection, I can not join two objects using a different condition than primary - foreign relationship, for example: Month > subscription_start_date and Month <= subscription_end_date
Is there any alternative solution to accomplish this? Thank you for your help.